Lens



Nov. 18, 24! 1,515,630

' H. H. STYLL ET AL 4 LENS Filed April 18 1922 4 INVENTOR 19 A. STVLL BY 50. T/LLVEP ATTORNEYS the county A further object at lens so as at lenses, which consists 4 ing the 4 a segment corresponding to the curvature of joinder new.

. D. TILLYE'B, OF SOUTHBBIDGE, MASSAUSETTS, AS- :sGNORS TO AMERICAN OPTICAL COMPANY, OF SO'U'TEBRIDGE, MASSACHUSETTS,

A VOLUNTARY ASSOCIATION OF MASSACEUSETTS.

, LENS.

Application filed A ril 18, 1922. serial to. 555,069.

To all whom it may concern:

Be it known that we, HARRY H. STYLL and EDGAR D. Truman, citizens of the United States, residing at Southbridge, in

of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Lenses, of which the followmg is a specification.

This invention relates to new and useful It improvements in lenses and more particularly to what is known as a bifocal lens. The main object of our invention is the production of a monocentric fused bifocal lens wherein the optical axis of the lens w is arranged at substantially the center portion of a lens of this character.

In theusual construction of bifocal lenses it is the practice to have an axis thru the major or distance portion ofthe lens and 2 an additional axis thru the reading portion of the lens and it is one of the main objects of our invention to provide an optical axis extending substantially thru the central portion of the lens.

of our invention is the provision of a monocentric bifocal lens whereinthe finished lens is provided with a pointed elliptical reading portion arranged within the major portion of the to provide a lar e major or distance ortion above the rea ing portion and a smal distance portion in the lower part of the lens. Still another purpose is to provide a process for making 'multifocal in surfacingv a recess in a glass blank to an optical surface inclined with respect to the main surface of the blank, also surfacing a segment of glass of different index of refraction approximatcurvature of the recess, constructing of the recess and securing the segment in the recess. The se cut and the blank on the recessed side t ereof are surfaced to an optical surface whose center of curvature is on a line passing through the center of curvature of the recess sur ace. andthe line of the segment and the blank.

ith the above and other objects. in view the invention consists in the novel features of construction, the combination and arrangement of parts hereinafter more fully set forth, pointed out in the claims and shown in the accompanying drawings, in which- Figure I is a front elevation of a lens illustrating the type of lens produced in the prior art.

Figure II is a similar view our improved lens.

Fi re III is a sectional view taken on illustrating the lib III-III of Figure I.

Figure IV is a sectional view taken on the lineIV.IV of Fi re II.

Fi re V is a ongitudinal section thru the b ank of ourjmproved lens.

Figure VI is a similar view illustrating the button in position prior to grinding, and Figure VII is a similar view illustrating a finished lens.

As set forth above, it has been customary in the manufacture of lenses of this ty e to extend the button to the lower edge 0 the major portion of the lens and provide two optical axes, one extending thru the major or distance portion of the lens and the other extending thru the center of the reading portion. It is, therefore, the purpose of our invention to provide a lens having an optical axis extending substantially thru the joining line between the major or distance portion of the lens and the minor or reading portion and, at the same time, if desired provide for a distance portion at the lower part of the lens.

In the construction of our we provide the major portion of the lens, formed of crown glass and indicated b the numeral 1, with a countersink 2 whic as indicated, is formed tilted with respect to the general plane of the major portion or blank in such a way that the center of curvatur of the button of the recess will lie" in theaxis of the blank, as best shown in Figure I In other words, by grinding the'recess in this manner the optical axes of the two corrections in the lens will be produced on the lineA-A, making the improved lens lens monocentric in form. In this way the inner wall of the countersink is in the form of a ledge or did, while in the outer portion there isno such cliff or wall the two curves intersecting each other. The result of this is that the segment or button 3 which is formed of flint glass is positioned in tilted relation to the major blank and having a different index of refraction from said blank. The flint button 3 may be secured by cement or fusion in the recess 2 and may be placed on either the inner or the outer side of the lens. The countersink bearing face is then ground ofi in a single continuthat by providing an such as are-experienced in the y 4 below the segment or rectly positioned ous curve so ground, as is indicated in Fig ure VII, that a portion of the button at the lower edge and adjacent major portion of the glass is ground away leaving a substantially elliptical shaped reading segment as at 5 in the finished lens with a distance vision portion 6- located thereabove, and in addition there is a second distance vision portion reading portion. Attention is also called to the fact additional distance portion at the bottom of the lenses it will be of great assistance to the wearer for-use in going up and down the stairs or other uses of this character.

The reading portion 5 is also correctly positioned within the major portion of the lens whereby the same can be readily used by the patient for the purpose desired. It is thought that the position of the reading portion 5 in our improved lens is more corthan the well known bifocal lens in use at the resent time in that the vision of the eye oes not have to be extended as low as inthe regular bifocal.

From the above description taken in connection with the accompanying drawing it will be readily apparent that we have provided a monocentric fused bifocal lens wherein the reading portion is of pointed elliptical form and arranged with respect to the major portion of the lens so as to prov1de for a small distance portion below the reading portion and a larger distance portion above the reading portion, which-givesa greater advantage to th the lens in that can be used for e person wearing the lower distance portion distant vision in a substantially vertical plane, such as looking downwardly in passing up or down a stairway or the like, and the upper distant ortion readily used for various distant ob ects. It will also be apparent that when the improvpd lens is completed the optical axis is so 0- sitioned as to. substantially eliminate dificulties due to displacementof the image as the eye passes from one field to the other present commercialforms of two-part lenses.

We would further call attention to gthe blank b0 other particular advantage attained by the present construction. This resides in the fact that by so positioning the segment receiving recess and segment that the lens will be substantially monaxial and then subsequently grinding away the segment sides of the lens so that the lower edge of the segment is spaced a distance from the edge of the major blank in place of extending out over that edge, as has been the previous practice. We are able to provide a wide and sufficiently high segment for ordinary reading purposes and, at the same time, to considerably reduce the thickness of the finished lens as compared with the prior art constructions. This is due to the fact that in the manufacture of two part bifocals the thickness of the lens is governed largely by the depth of the countersink, since it is.

centric form we do not mean that there can" be only one optical center of both reading and distance portion but that the line of sight passes from the distance to the reading portion without any sudden optical displacement at some portion of the lens.

at we claim is- I r 1. A- blank fora multifocal lens, comprising a blank body with a recess adapted to receive a' segment of higher index, the inner face of the recess being an optical surface whose center of curvature lies on a line normal to the blank body at one edge of the recess.

2. A blank for a multifocal lens, comprising a blank bbdy with a recess and an optical surface therein, the center of curvature of which lies approximately on a normal to the blank bod at one edge of the recess, and asegment 0 a piece of glass of difierent 1 index of refraction secured in said recess.

' 3. A blank, for a multifocal lens, com prising a blank body with a recess and an optical surface therein whose center of curvature lies a proximately on a normal to y at one edge of the recess, a segment of glass of difi'erent index of refraction secured in said recess, the outer face of the segment and the corresponding face of the blank being ground to a single optical surface.

por-

Q I to an ptieal surface inclined with reing its center of eurvature on e line Y spect to the main surface of the hlank surthrough the center-of curvature of the refacingta segment of glass of difierent mdex cess urface and the line .of joinder ithe of re action to the approximate curvature segment and blank. I

of the recess, securing said se ent in the recess, surfacin the blank an the segment HARRY H. STYLL. on the side to an eptie'al eurfeee hev- I EDGAR D. 

